<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        {{info | upper | lower}}
    </div>
    <script src="./node_modules/vue/dist/vue.js"></script>
    <script>
        Vue.filter('upper',function(val){
            return val.toUpperCase();
        });
        Vue.filter('lower',function(val){
            return val.toLowerCase();
        });
        let vm = new Vue({
            el: '#app',
            data() {
                return {
                    info: 'china'
                }
            },
            // 局部的
            filters:{
                upper:function(){

                }
            }
        })
    </script>
</body>

</html>